A starting point that I suggest is creating descriptions of key vocabulary for the unit. I don't recommend just copying the textbook definition, since you all can find that just fine individually, but write out definitions of the terms that make sense to you, examples that you can think of, tricks you have to help you remember them, etc. Got ideas for questions you think will probably be on the test? Got answers to unit focus questions? Got something you don't understand and want to ask classmates for their help or ideas? Take note, these are good study strategies!
Nature of Science Unit (includes atomic theory/density)
Indirect Measurement Unit
Classification
Ecology